Easy riding bicycle

ABSTRACT

A bicycle design includes a seat tube affixed to the chain stay at a fixed distance rearward of the bottom bracket so that the rider sitting on the saddle can comfortably fully extend one leg to place a foot flat on the ground or to use the proper full leg extension for pedaling. The rider sits comfortably upright on the saddle while pedaling and can pedal while standing up. Increasing the height of the saddle by extending the seat post tube for a taller rider increases the space between the saddle and the handle bars. The fixed distance may be on the order of about the height above ground of a heel of the rider&#39;s foot sitting on a properly adjusted conventional frame when the foot is outstretched to reach the ground and/or on the order of about a radius of a circle through which the pedals are moved during pedaling of the bicycle. The fixed distance is preferably in the range of about 4″ to 8″ and most preferably about 6″. The seat tube is preferably affixed to the chain stay frame member at an angle of about 66.5° and the head tube at an angle of about 68°.

RELATED APPLICATIONS

This application claims priority of copending U.S. provisional patentapplication Ser. No. 60/510,660 filed Oct. 10, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to bicycles and in particular, tobicycle designs which are easier to ride.

2. Description of the Prior Art

Conventional bicycles, often referred to as diamond frame bicycles, areavailable in many shapes and sizes. Conventional bicycle frames includea horizontal chain stay running between the axle of the rear bicyclewheel and the bottom bracket through which the pedals are mounted forrotation. The seat tube, which supports the seat or saddle, is typicallywelded to the bottom bracket. The down tube, running from the bottombracket to the head tube within which the front wheel rotates forsteering, is also typically welded to the bottom bracket. A top tube,running from the rear wheel axle to the head tube, also serves tostabilize the seat tube and may be made from a seat stay between therear axle and the seat tube plus an upper tube from the seat tube to thehead tube.

Conventional bicycle frames of this type are called diamond framesbecause the seat tube, chain stay, and seat stay form a first triangleand the seat tube, down tube and upper tube generally form a second,connected triangle with the down and upper tubes connected close to eachother at the head tube. In such conventional bicycle frames, the bottombracket through which the pedals are mounted for rotation, serves as acommon joint between the triangles and is welded or otherwise affixed tothe chain stay, seat tube and down tube. The top tube may be mountedlower towards the ground in versions requiring a lower stand-overheight, that is, the height of the bicycle frame between a rider's legswhen standing with both feet on the ground.

When conventional bicycles are adjusted for a particular rider, the seattube is typically extended so that the seat height allows the rider toextend one leg to reach the related pedal in it's furthest forwardposition. The proper full leg extension while pedaling, called hereinthe “proper full leg extension for pedaling”, includes a minor bend atthe knee so that the leg is not locked. When riding, the rider istypically leaning forward. When stopped, the rider is typically requiredto extend the toes on one foot to reach the ground and often will tiltthe bicycle toward the foot touching the ground in order to better reachthe ground. That is, when stopped, the seat is typically positioned toohigh for the rider to comfortably put both feet flat on the groundwithout tilting the bicycle.

Recumbent bicycles were developed to reduce the strain on the rider'sback by moving the bottom bracket and pedals further forward. Thispermits the rider to lean back and to operate the pedals at a different,less stressful angle. Allowing the rider to lean back, and moving thebottom bracket and pedals further forward, increases the wheelbase ofthe bicycle. When stopped, the rider can typically reach the ground withboth feet. Some riders consider this to be an awkward position becausethe rider's weight is behind the rider's feet rather than above therider's feet as it would be in a conventional bicycle. In addition, therider cannot stand up while pedaling as is commonly done for increasedperformance for example when pedaling uphill.

One currently popular variation for bicycle frames is called the“chopper” in which the bottom bracket and pedals are moved forward fromthe conventional bicycle frame position, but not as far forward as theywould be in a recumbent bicycle. The rider sits relatively erect withthe handle bars extended toward the rider. Conventional chopper designstypically provide neither the comfort and convenience of a conventionalbicycle frame design nor the reduced back strain of the recumbentdesigns.

What is needed is a bicycle design in which the bicycle is comfortableto learn to ride, to stand with and to ride. In particular, what isneeded is a bicycle frame design in which the rider can sit upright,stand up while pedaling if desired and being able to put one or bothfeet flat on the ground when stopped and the seat is adjusted for properleg extension for pedaling.

SUMMARY OF THE INVENTION

In accordance with a first aspect, a bicycle design is disclosed havinga chain stay supporting a rear bicycle wheel for rotation at a rearwardend of the chain stay, a bottom bracket affixed to the forward end ofthe chain stay for supporting bicycle pedals for rotation to propel therear bicycle wheel, a head tube for supporting a steerable front forkassembly including handle bars and front bicycle wheel, top tube anddown tubes affixed between the head tube and the rearward and forwardends of the chain stay, and a seat tube for supporting a saddle and theseat affixed to the top tube, the seat tube also affixed to the chainstay at a fixed distance rearward of the bottom bracket wherein theframe members are sized and configured (a) so that a rider sitting onthe saddle can comfortably fully extend one leg to place a foot flat onthe ground or to use proper leg extension while pedaling, and/or (b) sothat a rider sits comfortably upright on the saddle while pedaling,and/or (c) so that the rider can pedal while standing up, and and/or (d)so that increasing the height of the saddle by extending the seat tubefor a taller rider increases the space between the saddle and the handlebars.

The fixed distance may be on the order of about the height above groundof a heal of the rider's foot when the foot is outstretched to reach theground and/or on the order of about a radius of a circle through whichthe pedals are moved during pedaling of the bicycle. The seat tube isaffixed to the chain stay at an angle from the horizontal in the rangeof about 62° to 72°, 64° to 69° or preferably at an angle of about66.5°. The head tube may be affixed to the top and down tubes at anangle from the horizontal in the range of about 64° to 72°, 66° to 70°or preferably at an angle of about 68°. The angle of the head tube maypreferably exceed the angle of the seat tube by about 1.5°.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a bicycle according to the present disclosureadjusted for a short rider.

FIG. 2 is a top cut away view of the rear wheel and chain stay portionsof the bicycle shown in FIG. 1.

FIG. 3 is a side view of the bicycle shown in FIG. 1 adjusted for ataller rider.

FIG. 4 is a top view of the handle bars of the bicycles shown in FIGS. 1and 3.

FIG. 5 is an illustration of a preferred embodiment of the bicyclesshown in FIGS. 1 and 3, including chain, gearing, brakes, fenders andother components.

FIG. 6 is an illustration of a lady's model of the bicycle shown in FIG.5 with a rider.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In a conventional or diamond frame bicycle when the L saddle is loweredenough so that the rider can put one or both feet flat on the ground,riding or pedaling the bicycle is difficult because the distance fromthe saddle to the pedal is typically too short for the proper full legextension for pedaling.

Referring now to FIG. 1, one way to understand the bicycle frame designdisclosed herein is to imagine a rider sitting on saddle 14 with one ofhis feet flat on the ground as illustrated by leg extension 16, and thenthe rider lifts his leg by rotating it around the hip joint and keepinghis leg fully but comfortably extended at the proper full leg extensionfor pedaling until it is high enough off the ground to be in a suitableposition to pedal the bicycle as illustrated by leg extension 18. Bylocating the furthest pedal point from the saddle, illustrated as pedalpoint 20, and then positioning bottom bracket 65 to support the pedal atpedal point 20, the rider may put one or more feet flatly on the groundwhen stopped and also comfortably extend his leg to the proper full legextension for pedaling.

As shown in FIG. 1, extendable seat tube 52, which includes a seat postslidably engaged in the tube for supporting the saddle, was moved backfrom its conventional location at bottom bracket 65 by the insertion ofchain stay extension or horn 66 between chain stay fork 64 and bottombracket 65. Although a straight tube is preferred, the same effect canbe achieved with a tube which is bent or curved tube at the bottomtoward the bottom bracket. The length of horn 66, is preferably in therange of about 4″ to about 8″ and more preferably about 6″. The horntube length is about equal to the length of a pedal crank arm. It isalso about or the height of the rider's heel above the ground whensitting on a properly adjusted seat of a conventional frame andextending his toes to reach the ground. Horn 66 positions pedal point 20at the appropriate position for proper leg extension while pedaling. Inaddition, the insertion of horn 66 expands the rider's compartmentspace.

Referring now to FIG. 1, bicycle 10 is shown on ground level 12. Saddle14 is shown in a lower position, suitable for example, for a shorterrider at about 4′10″ tall. Leg dimension line 16 represents the distancefrom saddle 14 to ground 12 so that the rider can sit in saddle 14 andposition one or both feet flat on ground 12. Leg dimension line 18represents the distance from saddle 14 to pedal position 20 at which therider's leg is extended at the proper full leg extension for pedaling.Leg dimensions 16 and 18 are substantially equal. In practice, however,people tend to extend their legs more fully while standing than whenfully extending one leg to pedal a bicycle, so that the leg dimensionsare not exactly equal, but the difference is relatively slight.

Pedal position 22 represents the most forward pedal position on pedalcrank circle 24. Front wheel clearance dimension 26 represents therequired minimum clearance between pedal position 22 and front wheel 28to permit front wheel 28 to turn freely without interference between therider's foot at pedal position 22 and the closest part of front wheel28. Crank clearance dimension 27 represents the ground clearance betweenpedal position 21 and ground 12.

Front fork 31, in which front wheel 28 is mounted for rotation, extendsfrom the center of front wheel 28, upward at head tube angle 32,appropriate for comfortable steering. In the bicycle frame disclosed,head tube angle 32 is preferably 68°, but angles in the range of 66° to70° work well and angles in the range of 64° to 72° may be suitable inmany circumstances. Front fork 31 is mounted in head tube 30 forsteering rotation by handle bars 38. Adjustable stem 34 is positioned atthe top of head tube 30 to rotate with front fork 31 and is shownpositioned at angle 36, leaning in the direction of forward travel ofbicycle 10. Handle bars 38 are mounted through an opening at the end ofadjustable stem 34 and are shown positioned at angle 40 to stem 34.

Handle bars 38 preferably have a rise, shown as dimension 39 in FIG. 4,of about 4″ but rises in the range of 2″ to 6″ may also be used. Handlegrips 42 are positioned at the end of handle bars 38. The position ofhandle grips 42 may be adjusted to suit a comfortable arm reach of therider along handgrip upper quadrant 43 to permit the rider to be seatedin an upright position on saddle 14. Handle bars 38 are extendedsomewhat to be able elevate handle grips 42 in addition to positioningthe hand grips rearward toward the rider.

Referring now again to FIG. 1, chain stay 62 runs from the center oraxle of rear wheel 58 forward to bottom bracket 65. Chain stay 62 mayinclude rearward chain stay yoke 64, in which rear wheel 58 is mountedfor motion, and forward chain stay horn 66. The lower end of seat tube52 is positioned along chain stay 62, preferably at a strong point, suchas the intersection of chain stay yoke 64 and chain stay horn 66. Theterm chain stay horn is used to designate the support member between thechain stay yoke and bottom bracket. In a preferred embodiment, thissupport member may be somewhat horn or cone shaped as it increases indiameter, from its rigid mounting to the tubes or other members formingseat tube 52 and yoke 64, to be affixed to bottom bracket 65.

Chain stay 62, bottom bracket 65, upper and down tubes 68 and 72, headtube 30 and seat tube 52 form the frame members of the frame of bicycle10 and generally correspond to equivalent frame members of conventionaldiamond bicycle frames.

Referring now to FIG. 2, a top view of the above described portion offrame 10 including chain stay 62 is shown in greater detail. Inparticular, rear wheel 58 is supported for rotation by chain stay yoke64 of chain stay 62. Chain stay horn 66 and seat tube 52 are welded orotherwise affixed to the forward portion of chain stay yoke 64. Bottombracket 65, in which the pedals are mounted for rotation, is welded orotherwise affixed to the forward portion of chain stay horn 66 and alsosupports down tube 68. Dimension 67 represents the length of chain stayhorn 66. Chain stay horn 66 is used to move bottom bracket 65 forward ofthe point of support for seat tube 66 on chain stay yoke 64 so that therider is in a relatively upright position when operating the pedalsmounted for motion in bottom bracket 65.

Dimension 67 may conveniently be on the order of the typical distanceabove the ground of the rider's heel when a conventional bicycle isstopped. That is, when a conventional bicycle is stopped, the rider musttypically extend the toes on the leg being used to support the bicyclein order to reach the ground. The distance between the rider's heel andthe ground therefore represents the portion of the height of seat 14above the ground that prevents the rider from resting his foot flat onthe ground. In order to permit the rider to put one or both feet flat onthe ground when the bicycle is stopped, seat 14 may be positioned lowerby about dimension 67 so that the rider's foot when extended downward iscomfortably placed flat on the ground while chain stay horn 66 movesbottom bracket 65 sufficiently forward so that the rider's foot at theproper leg extension for pedaling reaches the pedal is at its furthestdistance from the rider, shown as pedal position 20 in FIG. 1.Alternately, dimension 67 may be on the order of the radius of the crankcircle, that is, the length of the pedal arm or support member extendingfrom the center of bottom bracket 65 to the axis of rotation of thepedal. Dimension 67 may be in the range of about 4″ to 8″ or about 6″.In a preferred embodiment, dimension 67 is sufficient when seat 14 isproperly adjusted for the proper leg extension while pedaling for therider to comfortably fully extend one or both legs to place his feetflatly on the ground.

Moving the pedals forward by about dimension 67 and lowering seat 14 byabout the same amount, with regard to a conventional frame in which thechain stay, seat tube and down tube are all affixed to bracket 65,allows the rider to put one or both feet flat on the ground when stoppedwhile providing the proper full leg extension for pedaling. Thisarrangement also puts the rider in a more natural and comfortableupright riding position while making it more convenient for the rider tohold the bicycle upright while standing or stopping.

Referring now again to FIG. 1, seat tube 52 is affixed to chain stayhorn 66 and chain stay yoke 64 by welding or other suitable means. Seattube angle 50, between horizontal chain stay 62 and seat tube 52 ispreferably on the order of about 66.50, but angles in the range of about64° to 69° work well and angles in the range of 620 to 720 may also beuseful.

Rear wheel 58 may be positioned as far forward as possible to minimizethe wheelbase of bicycle 10, but rear wheel 58 may be positioned aclearance dimension 60 behind seat tube 52.

Down tube 68 is connected to chain stay 62, and in particular to chainstay horn 66, at bottom bracket 65 and runs to a suitable position alonghead tube 30 so that closest dimension 70 provides clearance for frontwheel 28 and/or a front fender optionally, down tube 68 may bepositioned along head tube 30 to provide sufficient space in whichsuspension support 73 may be positioned above front yoke 31. Upper tube72 runs forward from the center of rear wheel 58 just below the top ofhead tube 30. Upper tube 72 may preferably be affixed to seat tube 52 byforming upper tube 72 in two sections, top tube 74 between head tube 30and seat tube 52 and seat stay 76 between seat tube 52 and the rearwardend of chain stay yoke 64 at the axle of rear wheel 58. For a lady'smodel bicycle, the rearward end of top tube 74 may be positioned loweralong seat tube 52, substantially below the forward end of seat stay 76.

Forward gusset 78 and rear gusset 80, positioned between the bottom ofupper tube 72 and head tube 30, and between the top of upper tube 72 andseat tube 52, add considerable strength and rigidity to the frame ofbicycle 10. These gussets may be used to compensate for the loss ofrigidity resulting from moving the lower end of seat tube 52 from bottombracket 65, where it would likely be positioned in a convention bicycleframe, to the end of chain stay horn 66 affixed to chain stay yoke 64.In a preferred embodiment, the diameter of the forward end of chain stayhorn is increased to provide the most support to bottom bracket 65. Inother words, the forward end of chain stay horn 66 may be formed toinclude an integral gusset to resist, for example, twisting forcesapplied by down tube 68.

The size of front and read wheels 28 and 58 may range from 12″ to 27″(or size 700C), but for adults from 4′6″ to 6′10″, a wheel size of 26″is currently preferred.

Referring now to FIG. 3, a single frame size of bicycle 10 may bemanufactured, shipped, sold and used for a wider range of rider sizesfrom a shorter to a taller rider, by adjusting the position of handgrips 52 and the position of saddle 14 in seat tube 52. Unlikeconventional bicycle designs, the rider compartment space, that is thespace between the saddle or seat 44 and seat tube 30, increases asbicycle 10 is adjusted for a taller rider. The increase in the ridercompartment space results from the relaxed position of the seat tube,that is, the seat tube angle as well both the fact that the head tubeangle is slightly larger and the fact that there is a significant risein the handle bars. In particular, while the height of the saddle may beadjusted by as much as about 12″ to 15″ by repositioning the seat postwithin the seat tube, the height of the handle bars may be adjusted onthe order of about 2″. These adjustments are preferably madeproportionally so that, for example, when the seat is adjusted halfwayup, at about 6″ to about 7.5″, the handle bar is also adjusted abouthalfway up, at about 1″. The additional range of adjustment for thetaller rider's outstretched arms is accomplished by rotating handle bars42 through an arc by adjusting handle bar angle 40.

The leg dimensions also increase for a taller rider, when the seat israised, allowing both the taller and shorter rider to both put theirfeet flat on the ground to support bicycle 10 when stopped when the seatis adjusted to provide proper full leg extension for pedaling to reachpedal position 20.

It is important to note that the increase in the rider compartment spaceand leg dimensions upon adjustment for a taller rider results from thedifference between seat tube angle 50 and head tube angle 32. In apreferred embodiment head tube angle 32 exceeds seat tube angle 50 byabout 1.5°. It is also important to note that the preferred angles forseat tube angle 50 discussed above permit a broad range of adjustmentfor the height of the rider while retaining the desirable qualities ofallowing a rider to place one or more feet flat on the ground whenstopped without tilting the bicycle, the proper full leg extension forpedaling, as well as the upright riding position as discussed above.

The position of saddle 44, suitable for a taller rider perhaps 6′21″tall, may be determined in the same manner as the position of seat 14shown in FIG. 1 for a shorter rider. In particular, leg dimension 46represents the distance required from saddle 44 for the taller rider toplace one or both of his feet flat on the ground while leg dimension 48represents the distance to pedal position 20 for a proper full legextension for pedaling. Saddle 44 is thereby positioned above and to therear of saddle 14 at seat tube angle 50. Seat tube 52 is positioned atseat tube angle 50 so that a saddle, such as saddle 14 can be adjustedin height along angle 50 to accommodate both the taller and shorterrider. The position of handle grips 42 may be adjusted to suit acomfortable arm reach of the taller rider along handgrip quadrant 43 topermit the taller rider to also be seated in an upright position onsaddle 44 while pedaling.

The included angle 54 between the leg dimension 16 and 18 for theshorter rider, shown in FIG. 1, is on the order of 45° while includedangle 56 between leg dimensions 46 and 48 for the taller rider shown, inFIG. 3, is on the order of about 37°.

A further advantage of the configurations of bicycle 10 shown herein isthe ability to ride while standing up. As noted above, it is common withconventional bicycles to occasionally stand up while pedaling forexample to ride up a steep hill. This advantage is lost withconventional recumbent bicycles, but is retained in bicycle 10. Inparticular, as clearly illustrated by stand up position reference 82,stand up pedaling is easily accomplished because head tube angle 32 andthe adjustments permitted for the position of hand grips 42, permit therider to stand up without interference. Upright riding positionreference 84 is also illustrated for clarity.

Referring now to FIG. 5, an alternate embodiment of bicycle 10 is shownin which top tube 74 may be formed in a convex upward curve permittingthe lower end of top tube 74 to be positioned lower along seat tube 52.The lowering of the end of top tube 74 reduces the stand-over height forthe comfort of the rider. Gusset 80 between top tube 74 and seat tube 50provides additional mechanical support and rigidity. Down tube 68 isformed in a similar and compatible convex downward curve which maximizesclosest dimension 70, for example to permit the use of a fender and/ormudguard. Gussets 78 and 80 are also shown with curved lower and upperedges, respectively which further enhance the rigidity, strength andoverall appearance of bicycle 10.

Further, seat stay 76 may also be formed in a slight concave upwardangle providing a pleasing sinuous continuation of top tube 74. Fenders,brakes, tires and rims, a wide seat, a chain guard and an in-hubtransmission are also shown.

Referring now to FIG. 6, in another alternate embodiment, a lady'sversion of bicycle 10 with a rider is shown in which top tube 74 isformed in a upwardly convex curve while the lower end of top tube 74 ispositioned substantially lower along seat tube 52. Lowering the end oftop tube 74 further reduces the stand-over height for the comfort of therider. Down tube 68 is formed in a similar and compatible convex curvewhich maximizes closest dimension 70. Gussets 78 and 80 are also shownwith curved lower and upper edges, respectively which further enhancethe appearance of bicycle 10.

Further, seat stay 76 is formed in a slight concave angle providing apleasing sinuous continuation of top tube 74. Fenders, brakes, tires andrims, a wide seat, a chain guard and an in-hub transmission are alsoshown.

1. A bicycle frame, comprising: a chain stay frame member supporting arear bicycle wheel for rotation at a rearward end of the chain stayframe member; a bottom bracket frame member affixed to the forward endof the chain stay frame member for supporting bicycle pedals forrotation to propel the rear bicycle wheel; a head tube frame member forsupporting a steerable front fork assembly including handle bars andfront bicycle wheel; top tube and down tube frame members affixedbetween the head tube frame member and the rearward and forward ends ofthe chain stay frame member; and a seat tube frame member for supportinga saddle and the seat affixed to the top tube frame member, the seattube member also affixed to the chain stay frame member at a fixeddistance rearward of the bottom bracket; wherein the frame members aresized and configured so that a rider sitting on the saddle cancomfortably fully extend one leg to place a foot flat on the ground orto use the proper full leg extension for pedaling.